Catalytic hydrogenolysis of heavy residual oils



Feb. 13, 1951 H. w. FLEMING CATALYTIC HYDROGENOLYSIS 0F HEAVY RESIDUAL UILS Filed May 17, 1948 3N OZ 9N LLVNOLLOVHJ mozmdmuw @885 :9:

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H.W. FLEMING A T TORNEKS Patented Feb. 13, 1951 CATALYTIC HYDROGENOLYSISOF HEAVY RESIDUAL OILS Harold W. Fleming, Bartlesville, Okla, assignorto Phillips Petroleum Company, a corporation of Delaware Application May 17, 1948, Serial No. 27,465

9 Claims. 3.

This invention relates to a process for the hydrogenolysis of petroleum oils. In a more speside aspect, it relates to a process for the treatment of heavy petroleum residues to produce improved gasoline and Diesel fuel. In another specific aspect, it relates to a single-chamber apparatus for hydrogenolysis and cracking of petroleum oils.

In the production of petroleum products by cracking and/or distillation, there are produced high-boiling, highly degraded residues, which cannot be readily utilized in many refining processes. Formerly, these fractions were sold as a fuel for railway locomotives or furnaces or were discarded. However, with the increasing demand for gasoline and Diesel fuel and a decreasing demand for heavy fuel oils, it is highly desirable that a rocess be found for converting these heavy residues to utilizable products. It is not possible to convert such heavy residues by the common methods used in catalytic cracking because this is usually done in the vapor phase and the boiling point of these residues is too high for such processes. It is not possible to conduct the catalytic cracking operations economically in the liquid phase because the catalyst wouldbecome immediately fouled and inactive. It is known that these heavy residues can be improved by hydrogenation at high pressure. This produces a low-grade gasoline which may be improved by reforming or isomerization.

I have discovered a process for the treatment of such high-boiling fuel oil or vacuum-reduced crude oil by a treatment with hydrogen at elevated pressures and temperatures. This process produces a good yield of premium Diesel fuel and relatively high octane number gasoline and at the same time, the catalyst life is comparatively long.

The principal object of my invention is to provide a process for converting heavy hydrocarbon residues into utilizable products.

Another object is to produce a relatively highquality gasoline and a high-quality Diesel fuel simultaneously from a single feed stock.

Another object is to provide an improved process for the hydrogenation of heavy hydrocarbon residues.

Another object is to provide. a single-chamber apparatus for hydrogenolysis.

Other objects and advantages will be apparent to those skilled in the art upon reading the following specification, claims and the appended drawing.

The single drawing is an .elevational view,

2. partly in section, showing a system wherein my invention may be practiced.

In the drawing, feed line, 2 provided with valve 3 joins coil 4 of heater s, from which heated feed flows through line 7 into reactor 8. A suitable distributor s distributes the oil over the upper catalyst bed II, which is composed of molybdenum oxide on alumina. The lower part l2 of the cata lyst bed is composed of molybdenum oxide on silica-alumina gel. Hydrogen flows from an external source, not shown, into manifold 13 controlled by valve l4. Lines l5 and I6 controlled by valves i! and it connect this manifold with the upper portion of reactor 8 and lines l9 and 2 I controlled by valves 22 and 23 connect manifold it with reactor 8 at the point of the interface between the two catalyst layers. Line 24 controlled by valve 26 is provided for introducing bottoms from the fractionating zone, hereafter described, into a lower portion of reactor 8. The reaction products are withdrawn from reactor 8 through line 2? to a high-pressure separator 28, and the separated hydrogen, together with small amounts of light hydrocarbons, flows through line 29 and pump 3| to purifier 32 for removal of sulfur compounds and/or light hydrocarbons. The purified hydrogen may be removed from the system through line 33 controlled by valve 34 or may be reintroduced into the reactor 3 through mania fold l3 which is connected to line 33 by line 36 controlled by Valve 31.

Liquid hydrocarbon products are removed from high-pressure separator 28 through line 38 to stabilizer 39. A portion of the light gases may be removed from stabilizer 39 through line 4| controlled by valve 42. The remaining hydrocarbons are removed from a lower portion of stabilizer 39 through line 43 into a fractionating zone 44, from which a gasoline fraction is res moved through line 4% controlled by valve 41. A Diesel fuel fraction may be removed through line 48 controlled by valve 49. The bottoms from the fractionating zone may be removed to an external storage, not shown, through line 5| controlled by valve 52 or they may be caused to flow through line 53 controlled by valve 54 and pump 56 to be reintroduced into the hydrogenation zone either through line 2 with the original feed or through line 24 into a lower portion of reactor 8.

Operation In the hydrogenolysis of .a topped crude, molybdenum oxide on silica-alumina gives good conversion to high-quality products. At temperatures between 850 and 900 F. and at by.

narily not used for hydrogenolysis.

drogen pressures greater than 2,000 p. s. i. g., the catalyst life is relatively long. However, topped crude is good refinery cracking stock and is ordi- When vacuum-reduced crudes or fuel oils are treated in the manner just described, it is found that, due to the heavy, relatively non-volatile nature of the charge, it is in liquid phase during the initial portion of the residence time in the reactor. When molybdenum oxide on silicaalumina is used as the catalyst, excessive coking by the heavy residues takes place, and the reactor and catalyst become quickly fouled. On the other hand, by the use of a'molybdenum oxide on alumina catalyst, a vacuum-reduced crude or fuel oil can be converted, with long catalyst life and very little coking. However, the gasoline produced with the latter catalyst has a relatively low octane number and is not suitable for use as motor fuel without further upgrading. Since this catalyst is not an extremely active catalyst for splitting and isomerization, the formation of light gases, which dilute'the hydrogen, is held to a minimum.

I propose to convert fuel oils or vacuumreduced crude oils of low economic value into saleable gasoline and premium Diesel fuel by conversion of such oils in a single reactor in which the initial portion of the catalyst bed is composed of"molybdenum oxide on alumina and the final portion of the bed is composed of molybdenum oxide on silica-alumina gel. By using these catalysts in the order named and by operating at the conditions listed hereafter, the reactions are controlled so that the feed stock is mildly cracked and hydrogenated in the first portion of the catalyst to form a suitable feed stock for the second portion of the catalyst. By this process, there is a minimum amount of carbon deposition in the 5,000 cubic feet'of hydrogen per barrel of oil feed.

The feed is converted in the molybdenum oxide on alumina portion of the catalyst bed with a minimum amount of cracking and light gas formation to lighter'materials without the formation of excess coke. The lighter material thus produced, which may resemble a-topped crude in its characteristics, is passed through the molybdenum oxide on silica -alumina gel catalyst, preferably with the further addition of hydrogen.

Theoil is cracked, hydrogenated, and isomerized to a high yield of gasoline of good octane number and premium Diesel fuel. By converting the hydrogen-poor material-in the initial portion of the bed comprising the-less active catalyst, the tendency for coking in the final portion of the bed is decreasedso that the operation may be allowed to proceed for relatively long periods without regeneration. r

In general, the process as practiced in connection with theattached Figure 1 is as follows: A feedstock, which may be vacuum-reduced crude oilor fuel oil, is passed from heater 0 through line 1 into reactor 0. This reactor is charged with a two-layer catalyst bed, the upper layer comprising molybdenum oxide on alumina and the lower layer comprising molybdenum oxide on silica-alumina gel. Hydrogen is admitted into the upper portion of reactor 8 through lines l5 and i0, and additional hydrogen is introduced into the reactor through lines l9 and 2! at the level of the interface between the two layers of catalyst. The temperature in the reactor is maintained at 825 to 910 F. and the feed rate may vary from 0.5 to 2.0 volumes of feed (hydrogen-free basis) per volume of catalyst per hour. The hydrogen is introduced into the reactor at a rate of 5,000 to 15,000 cubic feet of hydrogen per barrel of feed and the pressure in said reactor is maintained at 2,000 to 5,000 p. s. i. g. The major portion of the hydrogen may be added through conduit 50 and/or conduit 2|. The effluent from reactor 0 is .passed into high pressure separator 28, which may be operated at about 2,000 to 5,000 p. s; i. g., where the hydrogen is removed to be recycled through the system. The liquid fraction removed from high pressure separator 28 is run into stabilizer 30 where it is stripped of light gases and then run into a fractionating zone 40 for resolution into the desired fractions.

The volumes of the two catalysts in reactor 8 are ordinarily approximately equal. This relationship may, however, be varied considerably to suit specific requirements.

The preferred temperature range in the upper part of the reactor, that is, the part occupied by molybdenum oxide on alumina, is about 850-9l0 F. The preferred temperature in the lower part, which is occupied by molybdenum oxide on silicaalumina, is about 825 to 875 F. Since some temperature drop is ordinarily obtained when a pre heated feed is passed through a fixed catalyst bed, regulation of the two temperature ranges within the limits set forth is conveniently effected by the conventional process of preheating the feed to 850 to 910 F. and passing it to the reactor without using any other means of heating the reactor. Thus, the optimum temperature ranges for both catalysts are conveniently obtained and no special reactor design is necessary. Additional temperature control may be obtained, if desired, by regulating the temperature of the hydrogen entering the reactor through conduits l0 and 2| and by regulation of the temperature of the recycle stream circulated through conduits 53 and 24. V

The catalyst used in the upper part of reactor I1 is preferably prepared by depositing molybdenum trioxide on porous alumina. The finished catalyst preferably comprises approximately 0.5 to 10 weight per cent M003 and the remainder alumina. The catalyst in the lower part of the reactor preferably comprises about 0.5 .to 10 weight per cent M003, about 1 to 10 weight per.

cent A1203, and the remainder 8102. The individual catalyst compositions and the methods of preparation of the catalysts do not, however, constitute a part of this invention. Any of the methods disclosed in the art for the preparation of hydrogenolysis catalysts may be used. For example, the catalyst to be used in the upper part of reactor 3 might be prepared by soaking cal cined bauxite or activated alumina in. a solution of ammonium molybdate, separating the granular solid from the excess liquid, and converting the ammonium molybdate to M003 by ignition. The cata yst used in the lower part of the reactor might be prepared by asimilar procedure in which a commercial silica-alumina catalyst comprising;- for example, approximately" 2 alumina and the remainder silica, is substitutedf'or the bauxite or activated alumina.

The advantages of my invention will be furtheir understood from thefollowing examples:

Example I Fuel oil was treated with hydrogen at 5,000

'p'; s;.i'. g1 and. 875 F., using a space velocity of 1 volume of feed per volume of catalyst per hour and circulating 5,000 cubic feet of hydrogen per barrel of feed over a catalyst composed of molybdenu'm'oxideon alumina; 17 volume per cent of gasoline (ASTM octane number 44), and 37 volume per cent of. Diesel fuel having a cetane number of about 48 was obtained. The run was continuedfor more than 170 hours without any appreciable decrease in catalyst activity. No coking was observed.

Example II A. test using a vacuum-reduced crude oil feed was run at the above conditions for over 100 hours. The yield was 1'7 per cent gasoline (octane number 3,3) and 29 per cent Diesel fuel having a octane number greater than 60. There was decrease in catalyst activity during the test.

Example III Atest using fuel oilwas run at the conditions listed above over a catalyst consisting, of rnolyb denum oxide on silica-alumina and after only 13 hours, the run had to be stopped on account of coke formation. The yield was 35 per cent gasoline with an octane number of 56.

Example IV A vacuum-reduced crude was treated as in Example III and the catalyst became fouled with coke after 25 hours. 27 per cent of gaso ine (octane number 55) and 19 per cent of Diesel fuel were obtained.

Example V number 55) and 33 per cent Diesel fuel was obtained. The run continued for over 100 hours with no evidence of decreased catalyst activity or coke formation suflicient to cause the run to be shut down.

Example VI A vacuum-reduced crude oil is treated in a reactor, the infiuent half of which is charged with a molybdenum-oxide-on-alumina catalyst and the eflluent half of which is charged with a molybdenum-oxide-on-silica-alumina gel. catalyst. At a space velocity of 1, an inlet temperature of 875 F. a hydrogen feed of 5,000 cubic feet of hydrogen per barrel of feed, the yields are about volume per cent gasoline and about volume per cent Diesel fuel having a octane number of about 58. The ASTM octane number of the gasoline is 55, which may be increased to 75 by the additions of 3 ml. of tetraethyl lead. No decrease in the activity of the catalysts is obtained in more than 100 hours continuous operation.

As shown in the above examples, reduced crudes, vacuum-reduced crudes, and heavy fuel oils predominating in non-aromatic constituents may be subj ect'edlto hydrogenolysis in the pres"- ence of molybdenum oxide on alumina to produce Diesel fuel having a high octane number (e. g., usually 48 to 60 or higher) no inordinate carbon deposition is obtained. The gasoline produced, however, has a very low octane number (e. g., 35).

Reduced crudes may be subjected to hydrogenolysis in the presence of molybdenum oxide on silica-alumina to produce Diesel fuel having only slightly lower cetane number (e. g., 58 to 50) than that produced with molybdenum oxide on alumthe gasoline, however, has an octane number of to 60, which can be increased to '75 to by addition of tetraethyl lead. Heavier feed stocks. such as vacuum-reduced crudes and heavy fuel oils, on the other hand cannot be continuously processed with molybdenum oxide on silica alumina on account of inordinate carbon deposition.

By my invention, vacuum-reduced crudes and heavy fuel oils may be converted to high-quality gasoline and Diesel fuel in a single operation, and the outstanding advantages of each of the catalysts described may be realized and the disadvantages substantially eliminated. The preferred heavy fuel oil feed stocks for this process are those predominantly non-aromatic, for these yield better Diesel fuel and the gasoline produced shows greats improvement than highly degraded fuel oils. The highly degraded, highly aromatic fuel oils produce poorer Diesel fuels. The gasoline from these stocks processed by the method of this invention are of excellent quality (about '70 plus ASTM number), but this gasoline shows less actual --crease in octane number over that obtained by processing with molybdenum on alumina catalysts than do the gasolines produced from predominantly non aromatic fuel oils.

While I have described a preferred embodiment oi my inven ion and one which has particular advantages, various obvious changes may be made by those skilled in the art without departing from the spirit of my invention.

Having now described my invention, I claim:

1. A process for the hydrogenolysis of heavy residual oils Which comprises passing the heavy residual oil downward through a reactor in contact with a catalyst which comprises an upper layer of molybdenum oxide on alumina at a temperature of 850-910 and a lower layer of molybdenum oxide on silica-alumina, at a temperature of 825 to 875 F. and a hydrogen pressure of 2,000 to 5,000 p. s. i. g.

2. A process for the hydrogenolysis of heavy residual oil which comprises passing the heavy residual oil downward through a reactor in contact with a catalyst comprising an upper layer of molybdenum oxide on alumina and a lower layer or molybdenum oxide on silica-alumina at a space velocity of 0.5 to 2.0 liquid volumes of feed per volume of catalyst per hour, adding hydrogen to said reactor at a rate of 5,000 to 15,000 cubic feet of hydrogen per barrel of feed, and maintaining a temperature of 850 to 010 in said upper layer and a temperature of 825 to 875 in said bottom layer.

3. A process for the hydrogenolysis of heavy residual oil which comprises passing the heavy residual oil downward through a reactor in contact with a catalyst comprising an upper layer of molybdenum oxide on alumina. and a lower layer of molybdenum oxide on silica-alumina at a space velocity 0.5 to 2.0 liquid volumes of feed per volume of catalyst per hour, adding hydrogen to .said reactor at a rate of 5,000 to 15,000 cubic feet of hydrogen per barrel of feed, and maintaining a reactor pressur of 2,000 to 5,000 p. s. i. g., a temperature of 850 to 910 F. in said upper layer and a temperature of 825 to 875 F. in said bottom layer.

4. A process for converting heavy residual oils into lighter oils which comprises passing the heavy oil through a reactor at a space velocity of 0.5 to 2.0 volumes of feed per volume of catalyst per hour in contact with a first catalyst layer comprising molybdenum oxide on alumina and then through a second catalyst layer comprising molybdenum oxide on silica-alumina, at a reactor temperature of 825 to 910 F., introducing hydrogen into said reactor at a rate of 5,000 to 15,000 cubic fee-J of hydrogen per barrel of feed, and removing the reaction products from said reactor to a separating zone for resolution into the various fractions.

5. A process for converting heavy residual oils into lighter oils which comprises passing the heavy oil through a reactor at a space velocity of 0.5 to 2.0 volumes of feed per volume of catalyst per hour in contact with a first catalyst layer comprising molybdenum oxide on alumina and then through a second catalyst layer comprising molybdenum oxide on silica-alumina, at a reactor temperature of 825 to 910 a reactor pressure of 2,000 to 5,000 p. s. i. g., introducing hydrogen into said reactor at a rate of 5,000 to 15,000 cubic Y feet of hydrogen per barrel of feed, and removing the reaction products from said reactor to a separating zone for resolution into the various fractions.

6. The process of claim wherein said first catalyst layer comprises 0.5 to 10.0 weight per cent M003 and 90 to 99.5 weight per cent A1203 and said second catalyst layer comprises 0.5 to 10.0 weight per cent M003, 1.0 to 10.0 weight per cent A1203 and 80.0 to 98.5 weight per cent SlOz.

'7. A process for converting heavy residual oils which comprises passing the heavy oil through a reactor at a pressure of 2,000 to 5,000 p. s. i. g. and

a space velocity of 0.5to 2.0 liquid volumes of feed per volume of catalyst per hour in contact with a first catalyst layer comprising molybdenum oxide on alumina at a temperature of 850 to 910 F. and then through a second catalyst layer comprising molybdenum oxide on silica alumina at a temperature of 825 to 875 F., introducing hydrogen into said reactor at a rate of 5,000 to 15,000 cubic feet of hydrogen per barrel of feed, and removing the reaction products from said reactor to a separating zone for resolution into the desired fractions.

8. The process of claim "7 wherein said first catalyst layer comprises 0.5 to 10.0 weight per cent M003 and to 99.5 Weight per cent A1203 and saidsecond catalyst layer comprises 05120 10.0 weight per cent M003, 1.0 to 10.0 weight per cent A1203 and 80.0 to 98.5 Weight per cent SiOz.

9. A process for the hydrogenolysis of heavy residual oils which comprises passing the heavy residual oil downwardly through a reactor in contact with a catalyst which comprises an'upper first layer of molybdenum oxide on alumina and a lower second layer of molybdenum oxide on silica-alumina, at a temperature of 825 to 910 F. and a hydrogen pressure of 2,000 to 5,000 p. s. i. g. HAROLD W. FLEMING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Kanhofer Feb. 15, 1944 

1. A PROCESS FOR THE HYDROGENOLYSIS OF HEAVY RESIDUAL OILS WHICH COMPRISES PASSING THE HEAVY RESIDUAL OIL DOWNWARD THROUGH A REACTOR IN CONTACT WITH A CATALYST WHICH COMPRISES AN UPPER LAYER OF MOLYBDENUM OXIDE ON ALUMINA AT A TEMPERATURE OF 850-910* F. AND A LOWER LAYER OF MOLYBDENUM OXIDE ON SILICA-ALUMINA, AT A TEMPERATURE OF 825 TO 875* F. AND A HYDROGEN PRESSURE OF 2,000 TO 5,000 P. S. I. G. 